1. Field of the Invention
The present invention relates to apparatus for reading wireless tags, and to an apparatus, system, and program for inferring the status of the wireless tags.
2. Description of the Related Art
The technology of placing wireless tags in roadways and other public facilities to provide location-specific information to moving persons has reached the initial stage of deployment. In a system described in Japanese Patent Application Publication No. 2002-165825 and illustrated in the block diagram in FIG. 1, for example, wireless tags are embedded in guidance blocks provided in paved walkways to aid visually impaired pedestrians. The pedestrian has a wireless tag reader 20 including an electronic cane operable to communicate with the wireless tags 1301 and a data communication device operable to communicate with a guidance information database 1303 disposed at a central site. When the pedestrian's electronic cane reads an identification number from a wireless tag 1301, the data communication device queries the guidance information database 1303 to obtain corresponding information, which is provided to the pedestrian by audible means.
In an intelligent traffic system described in Japanese Patent Application Publication No. 2005-293348, wireless tags are embedded in roads to assist drivers of motor vehicles. A wireless tag reader mounted in a vehicle reads information stored in the wireless tags as the vehicle speeds past, and advises the driver about road conditions ahead.
Since the wireless tags in these and other such systems are generally installed in heavily trafficked outdoor locations, they are subject to wear and tear and are exposed to the elements. These factors can cause tags to malfunction, denying needed information to the user. Japanese Patent Application Publication No. 2002-230109 therefore proposes an inspection system in which a vehicle equipped with wireless tag communication equipment is driven over a course along which wireless tags are installed to determine the operational status of the tags.
The proposed inspection system is labor-intensive, however, as it requires inspection personnel to operate the vehicle and tour all sites where wireless tags are installed. Since labor-intensive inspection tours tend not to be made at frequent intervals, the proposed system is also slow in identifying inoperable tags.